Slot type separator



Dec. 14, 1965 B. HARROD, JR, ETAL 3,223,237

SLOT TYPE SEPARATOR Filed Jan. 18, 1962 IN VENT ORJ' Edgar B. Harrod Jr.

Ed 0r 7? Stevens ATTORNEY United States Patent 3,223,237 SLOT TYPE SEPARATOR Edgar B. Harrod, .lr., Frederick, and Edgar T. Stevens,

Myersville, Md., assignors to the United States of America as represented by the Secretary of the Army Filed Jan. 13, 1962, Ser. No. 167,203 2 Claims. (Cl. 2092) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to us of any royalty thereon.

This invention relates to a device for separating and classifying small water-borne insects. More specifically, this device has been designed to separate and classify male mosquito pupae and female mosquito pupae from liquid containing male and female pupae, larvae, food and debris particles.

It is extremely desirable incarrying out insect pupae experimentation to know the number of females and males within a certain test group. Sometimes it becomes necessary not only to separate large numbers of male pupae from the female pupae and vice versa, but it is also necessary to recombine them in a definite proportion in order that certain experiments can be conducted. An example of such experimentation is the sterilization of male pupae. First, the males are separated from the females. Then they are subjected to a source of radioactivity, after which the males and females are recombined in order to determine the sterilization results.

Fortunately, female pupae are larger than the male pupae and the male pupae are larger than the larvae. While it may appear that a solid separation could easily be carried out, such is not the case. The reason is that the pupae and larvae are live, air breathing creatures which swim rapidly to and fro. Since these creatures are alive, it is necessary to separate them without killing them by drowning or crushing. We have devised an apparatus which will accomplish this separation with a high degree of accuracy and without appreciable mortality. The sep aration is accomplished by passing the liquid bearing pupae and larvae through two slotted orifices, the first being wider than the second. Wash water must be carefully regulated so that it will not crush the pupae against the slotted wall, but it must have sufficient force in order to prevent the pupae and larvae from swimming upstream thereby avoiding the separation. We attain this separation by the mechanism illustrated in the accompanying drawing which is an isometric view of the entire device.

The Pupaerator (see FIG. 1) consists of a box type frame 1, having an underside fiat bottom 2, two side rails 3, upper side 4 and an opened lower side 5. Above the bottom 2 of the box is a smooth surface plate 6 made of /4 inch thick safety glass fitted snugly into the box. Located in the right and left side rails '3, at /2 inch intervals, are 23 grooves 7, /s inch wide by /s inch deep. These grooves 7 extend perpendicularly from the top of the side rails 3 to longitudinal grooves 8 located at the surface of the plate 6 at the open end of the box frame and extending on a 07 angle from the plate 6 toward the rear of the box. When bafiies 9 and 10 are placed in the vertical grooves 7, the bottom ends of the baflies 9 and 10 rest on the bottom of the longitudinal grooves 8 thus forming slots 11 and 12 between the bottoms of the bafiles 9 and '10 and the plate 6. Due to the /2 inch spacing of the vertical grooves 7 and the 07' slope of longitudinal grooves 8 that the baflies 9 and 10 rest on, there is a .004 inch difference in adjacent slot sizes, the slot dimensions decreasing toward the open end of the frame. These dimensions have been selected for a particular type of insect. Other dimensions would be used for other sizes of insects. An adjustable device to take the place of longitudinal grooves 8 could easily be designed in order to vary this slope. For example, an adjustable metal strip could be substituted for the longitudinal grooves 8. These longitudinal metal strips could be built in at the top portions of the side rails so that the baflies 9 and 10 would rest on them, or they could be built in on the side walls in exactly the same location of the present longitudinal groove 8. Other ways of course can be devised to produce this adjustable slope which in turn can produce many more diiferent slot sizes. A distribution plate 13, A; inch thick on an angle of approximately 30 from the plate 6 is fixed at the closed end of the frame. One rear leg 14 and two front legs 15 are pivoted for angle adjustment and leveling. A collection trough 16 is located across the open end of the frame and is fitted with a rubber tube 17 for distributing the male 18 and the female pupae 19 and larvae 20 into collection pans.

The pupaerator is set at an angle of approximately 20 from horizontal by adjusting the rear leg 14 and is leveled across the width by adjusting one of the two front legs 15. The solution 21 containing the pupae '18 and 19, larvae 20, etc., is directed from the feed tube 22 onto the distribution plate 13 where it is spread out by impact with the distribution plate 13. The solution 21 then flows down the inclined plate 6 carrying the pupae 18 and 19 and larvae 20 to the first slot 11 formed by bafiie 9.

The slot 11 is preadjusted in width so that the male pupae 1-8 and the larvae 20 pass through the slot 11 and on down the plate 6 to the second slot 12 while the female pupae '19 are retained at the first slot 11. The second slot 12, formed by a bathe 10, is preadjusted in width to retain the male pupae 18 and allow the larvae 20 to pass through. The larvae 20 are then washed into a collection trough 16 mounted at the end of the box frame 1 and are then directed into suitable containers through the rubber tube 17.

When a sufiicient quantity of pupae are collected to nearly fill either the first slot 11 or the second slot 12, the feed solution 21 flow is stopped and tempered tap water 23 from tube 24 is directed onto the distribution plate 13 in a similar manner to the feed solution 21 flow. This water 23 flushes down any pupae 18, 19 and larvae 20 remaining on the distribution plate 13 or on the plate 6.

After a few seconds it will be observed that the flow of larvae 20 through the second slot 12 has ceased. At this time separation is complete. With the flushing water 23 still flowing, the bafiie 10 forming the second slot 12 is manually raised approximately .020 inch thus allowing the flushing water 23 to carry the trapped male pupae 18 through the then enlarged slot 12 to the collection trough. These pupae 18 are then directed to a suitable container through the rubber hose 17. With the second slot enlarged, the procedure is repeated at the first slot 11 to collect the female pupae 19. After this collection is made, the flow of water 23 is stopped and the two baflies 9 and '10 are lowered to the original operating position, ready to start another separation cycle.

The normal concentration of larvae and pupae in the feed solution is l per ml. The proper feed flow rate is approximately 4 liters per minute at a two-foot head pressure. This combination of conditions were used in a testing program in which more than 116,000 Aedes aegypti mosquitoes were separated. The test results show that 45% of the mosquitoes that lived to become adults were female, 55% were male. Our mechanism collected 36% of these adults on a slot size of .048 inch, 98% of which were female, 50% of the adults were collected on a slot size of .039 inch, 92% of which were male.

The pupaerator was designed to separate mosquito pupae, however, it is reasonable to assume that it will separate other water-borne insects if there is a difierence in the size of the male and female pupae.

The basic design as presented is adaptable to mechanization, automation, continuous operation and increased capacity. Moreover, this device can be used also as a classifier. By taking a representative sample of liquid bearing larvae and pupae, the ratio of female to male larvae can be statistically determined in a much larger volume liquid bearing pupae and larvae.

It is therefore easily seen that we have invented a dualpurpose device which separates live material accurately without causing appreciable mortality.

We claim: 1

1. A device for the separation of pupae of live waterborne insects comprising a container having an inclined bottom, side walls, an upper end wall and a lower end wall; said side walls each having a complementary first guide means positioned lengthwise along its interior; said first guide means being biased toward the container bottom from the upper to lower end along theentire length thereof; said side walls each having a plurality of complementary second guide means along its interior and positioned substantially normal to said first guide means and in manifold contact therewith; bafile'means extending the Width of the container and slidably positionable in any of the complementary pairs of second guide means and in abutting contact with said first guide means; whereby the distance between the 'bottom edge of the baffle means and the container bottom is varied as the baffle means is positioned in the different complementary pairs of second guide means; means for uniformly flowing pupae-containing water onto the bottom of the container above the bafile means, and collecting means attached to the bottom of the container at the lower end thereof.

2. A device in accordance with claim 1 comprising two baffle means spaced from each other and positioned in any of the complementary pairs of second guide means and in abutting contact with the first guide means.

References Cited by the Examiner UNITED STATES PATENTS 2,221,024 11/1940 HOOd. 7 2,662,639 12/1953 Novak 209-2 3,032,381 5/1962 BOlO 219-17 3,097,161 7/1963 Dudyak 209 137 X FOREIGN PATENTS 307,852 3/1929 Great Britain. 405,874 2/1934- Great Britain.

HARRY B. THORNTON, Primary Examiner.

EDWARD H. MICHAEL, Examiner. 

1. A DEVICE FOR THE SEPARATION OF PUPAE OF LIVE WATERBORNE INSECTS COMPRISING A CONTAINER HAVING AN INCLINED BOTTOM, SIDE WALLS, A UPPER END WALL AND A LOWER END WALL; SAID SIDE WALLS EACH HAVING A COMPLEMENTARY FIRST GUIDE MEANS POSITIONED LENGTHWISE ALONG ITS INTERIOR; SAID FIRST GUIDE MEANS BEING BIASED TOWARD THE CONTAINER BOTTOM FROM THE UPPER TO THE LOWER END ALONG THE ENTIRE LENGTH THEREOF; SAID SIDE WALLS EACH HAVING A PLURALITY OF COMPLEMENTARY SECOND GUIDE MEANS ALONG ITS INTERIOR AND POSITIONED SUBSTANTIALLY NORMAL TO SAID FIRST GUIDE MEANS AND IN MANIFOLD CONTACT THEREWITH; BAFFLE MEANS EXTENDING THE WIDTH OF THE CONTAINER AND SLIDABLY POSITIONABLE IN ANY OF THE COMPLEMENTARY PAIRS OF SECOND GUIDE MEANS AND IN ABUTTING CONTACT WITH SAID FIRST GUIDE MEANS; WHEREBY THE DISTANCE BETWEEN THE BOTTOM EDGE OF THE BAFFLE MEANS AND THE CONTAINER BOTTOM IS VARIED AS THE BAFFLE MEANS IS POSITIONED IN THE DIFFERENT COMPLEMENTARY PAIRS OF SECOND GUIDE MEANS; MEANS FOR UNIFORMLY FLOWING PUPAE-CONTAINING WATER ONTO THE BOTTOM OF THE CONTAINER ABOVE THE BAFFLE MEANS, AND COLLECTING MEANS ATTACHED TO THE BOTTOM OF THE CONTAINER AT THE LOWER END THEREOF. 